Mathematics 220
Homework for Week 3
Due: September 26, Friday
Problems from Chapters 2 of the 3rd edition of the text.
• 2.18, 2.20, 2.32, 2.48, 2.54, 2.60, 2.64, 2.68, 2.72
If you are using the 2nd edition, be careful — question numbers may not agree.
• Determine whether the following four statements are true or false, and justify your
answers (“true” or “false” is not sufficient).
(i) 8x 2 R, 8y 2 R, xy = x + y.
(ii) 8x 2 R, 9y 2 R s.t. xy = x + y.
(iii) 9x 2 R s.t. 8y 2 R, xy = x + y.
(iv) 9x 2 R s.t. 9y 2 R s.t. xy = x + y.